Shaping Tomorrow's Built Environment Today

Defend–in–Place: How HVAC Systems, Building Automation Can Help Hospitals Protect Against Fires

By: Mary Kate McGowan, Associate Editor, News

From ASHRAE Journal Newsletter, April 24, 2018

The National Fire Protection Association (NFPA) reported last year that U.S. fire departments responded to about 5,750 structure fires in health-care properties a year. Those fires resulted in an average of about two deaths, 157 injuries and $50.4 billion in direct property damage a year.

Unlike occupants in many other buildings who can exit or leave a building during a fire emergency, evacuation is more complicated in health-care facilities with critically ill or injured patients.

Hospitals are designed to support a defend–in–place fire emergency strategy minimizing the need to evacuate, and, to the extent possible, allow for patients to remain in place or relocate within the building. It requires specific building components and highly trained medical staff to provide patient safety during a fire.

Ron Westbrook, P.E., Member ASHRAE, chair of ASHRAE Technical Committee 9.6 Healthcare Facilities; and Michael Meteyer, P.E., Member ASHRAE, spoke about the defend-in-place concept applied to hospitals and the role HVAC systems play in supporting it during the 2018 ASHRAE Winter Conference in Chicago.

The presentations included an overview of standards and codes, which Meteyer said sometimes do not align, and a case study of a hospital building at the State University of New York Upstate Medical University in Syracuse, N.Y., where Westbrook is the assistant director of physical plant for utilities and operations.

“Evacuating hospitals is not easy, so the intent is to build defensible structures as much as possible with correct zoning and the devices, so you minimize those impacts,” Westbrook said.

Building automation systems play an essential role in limiting the spread of fire in health-care facilities, said Westbrook, and modern hospital design practice should feature automation and fire alarm detection systems that are coordinated with operation and evacuation plans as well as patient needs.

When communicating about disaster preparedness, engineers, firefighters, hospital officials and other stakeholders may not be using the same terminology or may define their terms in different ways, and “HVAC engineers need to understand that,” Meteyer said.

“Typically, you have two different code bodies (The International Building Code & NFPA) and different code authorities using different terminology. You’ve got to navigate with them and help them understand you and make sure you’re understanding what they’re saving,” he said.

Fire Safety Systems

On the building-side of preparedness, Meteyer, a mechanical engineer at Erdman in Madison, Wis., said hospitals are designed with multiple smoke compartments consisting of smoke barrier walls, doors and fire/smoke dampers protecting duct penetrations with the purpose of containing the fire and smoke.

In the event of a fire, the building construction will provide additional protection to contain the fire and smoke providing the staff time to relocate patients as needed to adjacent smoke compartments.

Keep in mind, some patients are on life support systems and are completely dependent on staff moving them to a safe spot, Meteyer said.

At times, the equipment must be moved with the patient. That introduces the challenge of making sure the equipment remains functional as it and the patient are being evacuated down a stairwell.  

Central air handling systems play a significant part in containment of smoke in a fire event.

“What is your air handler going to do when there’s smoke detected in a smoke compartment?” said Meteyer.

In many hospitals, the central air handlers serve multiple smoke compartments and on multiple floors.

“First and foremost, the air handling systems must be controlled such that they don’t make the situation worse by spreading the smoke around with the air handlers,” Meteyer said.

The most common approach is to isolate supply and return air from the smoke compartment with the fire. In many situations it is acceptable and more practical to isolate the portion of the floor by closing fire/smoke dampers at the shaft of the supply and return air from the air handler serving the area with the fire.

Westbrook said the fire boundaries need to be properly defined, and the fire safety devices need to be properly located and tested. In modern hospitals the fire safety systems should have active fire protection systems that include automatic devices, such as smoke and heat detectors, in rooms that automatically respond and isolate specific fire zones in case of an emergency, he said.

In the event of an emergency, the alarms within that zone would initiate a sequence of operation to isolate that zone from the rest of the floor or floors to limit the spread of smoke and flame.

Dampers in the supply air ductwork will close to prevent supplying ventilation air to that zone, and return air dampers close to prevent returning smoke to the supply fans where it could be circulated through the building. Dampers open and a dedicated smoke evacuation fan starts to exhaust smoke from the building.

Stairwell pressurization fans within that zone also activate to keep stair risers clear of smoke to allow safe exit from the building. Meanwhile, staff would remove patients from the zone to an adjacent zone or floor and begin prepping patients if they needed to be evacuated, Westbrook said.

Westbrook added that patient requirements can also impact the staff’s immediate response. Patients with compromised immune systems, such as those undergoing cancer treatment, are extremely vulnerable to infection. These patients are generally isolated to protective environment rooms as defined by the Facilities Guidelines Institute, with ventilation systems that provide positive pressurization to limit infections that are airborne transmissible. When ventilation systems to these areas are lost in response to alarm activation, the staff must move quickly to mask these patients for protection from infection.

Testing Challenges and Solutions

Sequencing the fire/smoke dampers to isolate or contain the smoke requires coordination among the fire alarm systems, fire/smoke dampers and the air handler controls.

“The best results are achieved with collaboration between the fire alarm and building automation programmers,” Meteyer said.  

These defend-in-place sequences involving the fire/smoke dampers and the air handler must be tested periodically.

If it is new construction, it must be tested prior to turning it over to the building owner, and again at the end of year one, and for hospitals every six years after that. 

“Certain fire alarm devices are required to be tested annually, but merely testing the device does not prove the integrity of the system,” said Westbrook. “Testing all elements as a system has considerable impacts on the delivery of service, so it is very difficult to schedule and complete. Much of the work has to be performed off hours to limit service interruptions, which is simply too costly.”

Some device manufacturer’s service group test components for warranty reasons and to maintain required codes or independent laboratory rating, he said.

To increase testing efficiency and ease, Meteyer said building owners should consider participating in the first tests since they will need to be able to repeat testing protocols a year later. Westbrook suggested HVAC engineers should have an organized, pre–planned procedure for the system’s programming and testing. He said contractors are more likely to buy into a practical plan.

“Trying to get everyone on the same page is one of the bigger hurdles that you’re going to encounter late in the process when you are trying to demonstrate functional operation with the facilities often changing needs,” he said.

Some simple steps that can really save time are to have the HVAC engineers individually identify or tag all the fire/smoke dampers. The fire alarm programmer and building automation programmer should use the same names for the fire/smoke dampers.

That allows for fast troubleshooting and for others to review the programs and identify errors prior to any actual testing. Electronic fusible links are another time saver that owners should consider having the HVAC designers specify.

The State University of New York Upstate Medical University has an overall matrix based on the building’s quadrants, Westbrook said. The hospital tests the fire alarm systems, damper actuators and tests the sequence of operations and devices annually, according to Westbrook.  Smoke and fire dampers are inspected and serviced every six years, in accordance with NFPA.

Changing Needs

A hospital’s needs change throughout the day and the hospital, Westbrook said. Patients’ needs vary by room, and the number of staff available to help evacuate patients at any time changes throughout the day and night.

The key to protecting against and isolating a fire emergency in a hospital is demonstrating active defend-in-place capabilities that are maintained and adapt based on facility changes, Westbrook said.

Westbrook recommended annually reviewing fire safety plans and testing the systems to accommodate for any changes that might invalidate the safety plans.

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